The present invention relates to a honeycomb core diaphragm, and more particularly, to a honeycomb core diaphragm containing, as a core material, a honeycomb material which is made from a thin plate of beryllium or a beryllium alloy.
In general, a diaphragm utilizing a honeycomb core is used specifically as a planar diaphragm because it has a greater stiffness than a diaphragm made of paper and, furthermore, its apparent mass is small. In the production of such diaphragms, it is desirable to use materials of high stiffness and low density in order to increase the efficiency of the diaphragm and to extend the piston motion zone. Thus, in view of molding ease, aluminum has heretofore been used to produce a honeycomb core diaphragm.
Beryllium is greater in stiffness than aluminum and, furthermore, its density is smaller than that of aluminum. If, therefore, beryllium could be used to produce a honeycomb core, there would be produced a honeycomb core diaphragm which realizes a piston motion of higher efficiency within a wider zone as compared with the conventional diaphragm containing an aluminum hoenycomb core. Beryllium, however, is difficult to mold, and a thin plate of beryllium has heretofore been produced only by a vacuum deposition method. In accordance with this method, it is impossible to produce a honeycomb core. Thus, a diaphragm using a honeycomb core made of beryllium or its alloy has not heretofore been produced.
It has been found that a thin plate of beryllium or its alloy produced by a super-rapid cooling method, i.e., by jetting molten beryllium through a nozzle onto a single roll or a pair of rolls rotating at a high speed to cool it abruptly on the surface of the roll, has a nearly uniform width and thickness and, furthermore, that the thin plate of beryllium or its alloy so formed has very good workability that permits press-forming at ordinary temperatures, because the crystal grains are dense and finely divided.